Thanks for your query, I have gone through your query. The pain and swelling across the jaw can be secondary to tooth infection, that has resulted in cellulitis involving masseteric and ptrerygomandibular space infection, which results in trismus. Nothing to be panic, consult an oral physician and get it evaluated. Once the diagnosis is confirmed we can treat accordingly either with root canal treatment or extraction of the tooth. Mean while you can take a course of antibiotics like amoxicillin and metronidazole(if you are not allergic) I hope I have answered your query, take care.